netfilter: nf_tables: use rcu chain hook list iterator from netlink d…

…ump path

Lockless iteration over hook list is possible from netlink dump path,
use rcu variant to iterate over the hook list as is done with flowtable
hooks.

Fixes: b9703ed ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Reported-by: Phil Sutter <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>

net/netfilter/nf_tables_api.c

@@ -1849,7 +1849,7 @@ static int nft_dump_basechain_hook(struct sk_buff *skb, int family,
 		if (!hook_list)
 			hook_list = &basechain->hook_list;
 
-		list_for_each_entry(hook, hook_list, list) {
+		list_for_each_entry_rcu(hook, hook_list, list) {
 			if (!first)
 				first = hook;